Short and Medium Baseline Reactor Neutrino Experiments

Speaker: Shengchao Li Virginia Tech

On behalf of: Yue Meng Shanghai Jiao Tong University

5/21/2019 SUSY2019 Content

• Neutrino oscillation • Short baseline reactor neutrino experiments • Daya Bay experiment • RENO experiment • Double CHOOZ experiment • Medium baseline reactor neutrino experiments • JUNO experiment

5/21/2019 SUSY2019 Neutrino Oscillation Three neutrino oscillation case:

UPMNS

atmospheric reactor solar

Very-

5/21/2019 SUSY2019 Short Baseline Reactor Neutrino Experiment

5/21/2019 SUSY2019 Why Short Baseline Reactor Neutrino Experiment

• Efficient in finding the mixing angle 휃 13 • Pure flavor source ( ) 20 • Large flux (2x10 /GWth) • Clean detection channel (Inverse Beta Decay) • Direct and unambiguous measurement

• Search for sterile neutrinos • Investigate the reactor antineutrino anomaly • Other interesting topics (reactor flux, CPT, Lorenz violation, etc.)

5/21/2019 SUSY2019 Detection Method • Inverse Beta Decay

(Energy Threshold 1.8 MeV) Flux(Arb.)

5/21/2019 SUSY2019 Current Generation of Short Baseline Reactor Experiments

Relative measurements for ϴ13 ; independent of the absolute reactor flux and spectrum Daya Bay(China) RENO(South Korea) Double Chooz(France)

5/21/2019 SUSY2019 3 zones(GdLS, LS, MO) Three Neutrino Oscillation Measurement DYB 1958 days RENO 2200 days DC 818 days

Plots from the follow-up results of 5/21/2019 SUSY2019 the collaborations @ Neutrino 2018 Length/Energy Curve DYB RENO

5/21/2019 SUSY2019 Oscillation Summary Assume NH Daya Bay: nGd: 2 sin 2휃13=0.0856±0.0029 2 −3 2 Δ푚푒푒 =2.52±0.07×10 eV nH: 2 sin 2휃13=0.071±0.011 RENO: nGd: 2 sin 2휃13=0.0896±0.0068 2 −3 2 Δ푚푒푒 = 2.68±0.14×10 eV nH: 2 sin 2휃13=0.094±0.015 2 −3 2 Δ푚푒푒 = 2.53−0.32+0.28×10 eV Double Chooz: nGd + nH: “Large” 휃13 has strong impact on 2 Mass Hierarchy determination! sin 2휃13=0.105±0.014 Results from Daya Bay, RENO, DC @ Neutrino 2018 5/21/2019 SUSY2019 Search for 3+1 Light Sterile Neutrino

• Theoretical interest DYB DYB+Bugey+MINOS • Non-SM particle • Hints of ~eV sterile neutrino: • LSND and MiniBooNE anomaly • Reactor neutrino anomaly • Daya Bay has multiple baselines to threeIntr groupsoduction of reactor -> relative Excluded

• If exists, Dayaspectral Bay would distortion see additional of sterile rate and spectral distortion frneutrinoom sterile neutrinos

1 EH1 EH2 EH3

)

e 3 n best fit n 3 n + sterile (illustration)

® Significantly reduced the allowed

e 0.95

n

(

P parameter space for future Δ휒2 = 휒2 3휈 − 휒2 3 + 1휈 searches. 0.9 = 134.7 − 129.1 = 5.6 0 0.2 0.4 0.6 0.8 Very-short baseline experiments: L / E [km/MeV] → p-value = 0.41 eff n DANSS, NEOS, PROSPECT, STEREO, 5/21/2019 SUSY2019 SOLID,CHANDLER…

4 Reactor Neutrino Flux Related Fuel evolution DYB Individual Antineutrino Flux measurement Spectra from 235U and 239Pu

Daya Bay

RENO

DYB: DYB(2019) R(Huber+Mueller) Disentangled spectra show the = 0.952 ± 0.014(exp.) ± 0.023(model) deficit come from 235U RENO: -> potential problem in the R(Huber+Mueller) 235U antineutrino spectrum = 0.918 ± 0.018(exp.)

5/21/2019 SUSY2019 Reactor Neutrino Spectrum and the “5MeV Bump” (In comparison with Huber-Mueller Model) Impact: • Experiments like JUNO use reactor spectrum information DYB: • Better understanding of reactor related nuclear physics

What people think might be the cause: 1. Forbidden decays contribute to the 5 MeV region 2. Old ENDF database predicted the bump RENO: 3. Arise from U-238, harden neutron spectrum in light- water power reactor 4. Error in ILL-spectra measurement 5. Improved agreement with recalculated summation model with updated databases DC:

Lots of progress..

5/21/2019 SUSY2019 Medium Baseline Reactor Neutrino Experiment

5/21/2019 SUSY2019 Jiangmen Underground Neutrino Observatory (JUNO)

JUNO is designed to resolve the neutrino mass hierarchy using precision spectral measurements of reactor antineutrino oscillations.

Optimal position for distinguishing between the mass hierarchies

Total thermal power will be 26.55 GWth 5/21/2019 SUSY2019 when JUNO will start data taking. Jiangmen Underground Neutrino Observatory (JUNO)

• Suppression of solar neutrino oscillation (Δ21 , 휃12 ) • “Large” 휃13

5/21/2019 SUSY2019 Jiangmen Underground Neutrino Observatory Keys: (JUNO) JUNO Central Detector 1. Optimal baseline for the detector 2. Large statistics 3. Superb energy resolution (3% @ 1 MeV) 4. Energy scale uncertainty <1% 5. Background reduction

5/21/2019 SUSY2019 Jiangmen Underground Neutrino Observatory

The signal signature: (JUNO) • Prompt photons from e+ ionization and annihilation (1-8 MeV). • Delayed photons from n capture on Hydrogen (2.2 MeV). • Time (Δt~200 μs) and spatial correlation.

Experiment Daya Bay Borexino KamLAND JUNO Target mass [tons] 20 /detector ~300 ~1,000 20,000 PE collection [p.e./MeV] ~160 ~500 ~250 ~1200 Photocathode Coverage 12% 34% 34% 75% Energy resolution @ 1 MeV ~7.5% ~5% ~6% ~3% Energy calibration 1.5% 1% 2% <1% JUNO will be the largest liquid scintillator detector and with the best energy resolution in the world 5/21/2019 SUSY2019 JUNOJUNO cali Calibrationbration st Systemrategy • The JUNO challenge is to keep energy scale uncertainty below 1%

5 complementary calibration systems under development using e-, e+, γ and n sources

Cable Loop System (CLS) Automatic calibration unit (ACU) 2D plane inside the vessel 1D along detector z-axis

Remotely Operated Vehicle (ROV) Guide Tube (GT) + Laser fiber system 2D around outer surface vessel 1D like, fixed position on PMT 3D anywhere in the vessel 5/21/2019 SUSY2019

5 Future Opportunities with JUNO • Measurement of the neutrino mass hierarchy • Observe “solar” and “atm” neutrino oscillations simultaneously 2 2 2 • Precise measurements of oscillation parameters, sin 2θ12 , Δm 12 , Δm ee (< 1% ) • Probing the unitarity of UPMNS to sub-percent level • Investigation from terrestrial and extra-terrestrial neutrino sources (like supernovae, solar, atmospheric, geo-neutrinos, etc.)

5/21/2019 SUSY2019 Summary

• Short baseline reactor neutrino experiments have made precise 2 2 measurement for sin 2휃13 and Δ푚 푒푒 • Updates on exclusion contour guides future sterile neutrino hunt • Antineutrino flux/spectrum measurement from short baseline experiment helps with better understanding of reactor behavior(watchman/monitoring)

• Next generation medium baseline neutrino experiment will determine mass hierarchy • Huge LS detector also allows research topics involving supernova, solar, atmospheric and geo-neutrino, etc.

5/21/2019 SUSY2019 Backup

5/21/2019 SUSY2019 Additional Topics with Reactor Neutrinos

• Search for the Neutrino Magnetic Moment via Neutrino-electron Scattering • Wave Packet and Neutrino Oscillation • Leggett-Garg Inequality and Neutrino Oscillation • Lorentz Violation and Neutrino Oscillation

5/21/2019 SUSY2019 Why we do short/medium baseline neutrino experiment

Two neutrino oscillation case:

Three neutrino oscillation case:

• Determine mass hierarchy

5/21/2019 SUSY2019 5/21/2019 SUSY2019